Most people connect the casting director with big name stars for movies, stage, and television productions. Yet, the casting director usually defers to the main director on lead roles. Instead, the casting director must work on fulfilling the roles of all spoken roles, and on supervising the employing of all extras.

In productions with alot of people, the casting director and their assistants will have to see thousands of people to fill hundreds of roles. The casting director usually gets some counseling from the director of the film so he or she can make decisions about who will be the strongest for the roles.
Fundamentally the goal of the casting director is to hire people who will fit with the director’s, and perhaps the producer’s, artistic aspirations. Normally, actors go through several casting calls.

In the begining, assistants may supervise auditions. If the assistants determine that the individual auditioning for a role may be good for a part, then the individual is given a callback. There may be several callbacks.

Different to extras or aspirant actors, most well-known stars don't have to go through as many callbacks to be seen by a casting director. A film director who wants a particular individual for a role may initiate this audition process, or the actor’s agent may initiate it. Often the casting director will immediately listen to a person read, or sing for a role, though callbacks may be required if the casting director has not made a final conclusion